GCN Circulars
GCN Circulars are rapid astronomical bulletins submitted by and distributed to community members worldwide. They are used to share discoveries, observations, quantitative near-term predictions, requests for follow-up observations, or future observing plans related to high-energy, multi-messenger, and variable or transient astrophysical events. See the documentation for help with subscribing to or submitting Circulars.
Search for Circulars by submitter, subject, or body text (e.g. 'Fermi GRB').
To navigate to a specific circular, enter the associated Circular ID (e.g. 'gcn123', 'Circular 123', or '123').
To navigate to a specific circular, enter the associated Circular ID (e.g. 'gcn123', 'Circular 123', or '123').
18177 results found.
- GRB 241026A: SVOM/GRM observation
- GRB 241025A: Swift/UVOT Detection
- GRB 241026A: GROWTH-India Telescope optical observations
- GRB 241026A Fermi GBM Analysis
- GRB 241026A: J-band observations with WINTER
- GRB 241025A: SAO RAS optical observations
- GRB 241026A: Las Cumbres optical detection
- GRB 241025A: Mondy optical observations
- GRB 241026A: Swift-XRT refined Analysis
- GRB 241026A: Enhanced Swift-XRT position
- GRB 241026A: KAIT optical observations
- GRB 241026A: COLIBRÍ Detection of the Optical Counterpart
- GRB 241026A: SAO RAS observations of possible optical afterglow
- GRB 241026A: Prompt enhanced Swift-XRT position
- GRB 241026A: Swift detection of a burst
- Swift GRB241026.95: Global MASTER-Net observations report
- GRB241025A: 1.3m DFOT optical afterglow detection
- GRB 241025A: GROWTH-India Telescope optical observations
- GRB 241025A: COLIBRÍ Detection of the Afterglow
- GRB 241025A: Swift-XRT refined Analysis
- GRB 241025A: Fermi GBM Observation
- IPN triangulation of GRB 241022A (short/hard)
- LIGO/Virgo/KAGRA S241009l: Upper limits from Swift/BAT-GUANO
- GRB 241025A: GRANDMA and Kilonova-Catcher optical afterglow detections and upperlimits
- EP 241021a: Swift-XRT observations
- Swift GRB 241025A: Global MASTER-Net observations report
- EP241025a (GRB 241025A): EP observations update
- EP 241021A: Swift ToO observations
- GRB 241025A: Enhanced Swift-XRT position
- GRB 241025A: NOT spectroscopic redshift of z = 4.20
- GRB 241025A: DDOTI Afterglow detection
- EP241025a (GRB 241025A): EP on-board trigger and autonomous follow-up observation
- GRB 241025A: SVOM/GRM observation
- GRB 241025A: TRT optical afterglow observation
- GRB 241025A: Swift detection of a burst with an optical counterpart
- GRB 241018A: EP-FXT afterglow detection
- GRB 241018A: Mondy optical upper limit
- GRB 241018A: SVOM/VT further analysis and counterpart confirmed
- GRB 241018A: GROWTH-India telescope optical upper limit
- GRB 241018A: Swift-XRT observations
- GRB 241018A: NOT optical observations
- GRB 241018A: Swift ToO observations
- GRB 241006A: VIRT Optical Upper Limit
- GRB 240727A: VIRT Optical Upper Limit
- GRB 241016B: Fermi GBM Observations
- GRB 241017A: Swift-XRT observations
- GRB241017a: Liverpool Telescope observations of XRT uncatalogued sources
- GRB 241001A: EP-FXT afterglow detection
- GRB 241017A: GROWTH-India Telescope optical upper limit
- GRB 241016B: Swift/BAT-GUANO localization skymap of a short burst
- GRB 241017A: Swift ToO observations
- GRB 241010A: Swift-BAT refined analysis
- GRB 241013B: Fermi GBM Observation
- GRB 241013B: Swift/BAT-GUANO localization skymap of a burst
- GRB 241009A: LCO optical upper limits
- GRB 241009A: GRANDMA optical upper limits
- GRB 241009A: Swift-XRT afterglow detection
- GRB 241010A: JinShan optical observations and potential host galaxy
- GRB 241006A: ATCA Radio Upper Limits
- GRB 241010A: Swift-XRT refined Analysis
- Swift GRB 241010A: Global MASTER-Net observations report
- GRB 241010A: J-band observations with WINTER
- GRB 241010A: Enhanced Swift-XRT position
- GRB 241010A: LCO optical observations
- GRB 241010A: Swift detection of a burst with an optical counterpart
- GRB 241006A: Swift-BAT refined analysis
- GRB 241009A: Swift ToO observations
- GRB 241002B: Swift-XRT afterglow detection
- GRB 241002A: NOT optical upper limits
- GRB 241006A: GRANDMA optical upper limits
- GRB 241006A: Swift-XRT refined Analysis
- GRB 241006A: PRIME near-infrared upper limits
- GRB 241006A: Swift/UVOT Upper Limits
- GRB 241006A: SVOM/VT follow-up and optical upper limit
- GRB 241001A: Swift-XRT afterglow detection
- GRB 241006A: Enhanced Swift-XRT position
- GRB 241006A: Swift detection of a burst
- Swift GRB241006.91: Global MASTER-Net observations report
- GRB 240930B: SVOM/C-GFT optical upper limit
- GRB 240930B / EP 240930a: SVOM/GRM observation
- GRB 241002B: Fermi GBM Observation
- GRB 241002B: Swift-XRT observations
- GRB 241002A: Swift-BAT refined analysis
- GRB 241002B: Swift/BAT-GUANO localization skymap of a burst
- GRB 241002B: Swift ToO observations
- GRB 241002C: Swift-XRT observations confirm the source to be EI Eri
- GRB 241002C: Swift ToO observations
- IPN triangulation of GRB 240930B / EP 240930a
- GRB 240930B: CALET Gamma-Ray Burst Monitor detection
- GRB 241002A: Swift/UVOT Upper Limits
- GRB 241002A: Swift-XRT refined Analysis
- GRB 241002A: LCOGT Optical Upper Limits
- GRB 241001A: GRANDMA and Kilonova-Catcher optical afterglow detection and upper limits
- GRB 241001A: Swift/UVOT Detection
- GRB 241001A: Swift-XRT observations
- GRB241001A: optical afterglow candidate
- GRB 241002A: 1.5m OSN optical upper limit
- GRB 241002A: Enhanced Swift-XRT position
- GRB 241002A: Swift detection of a burst
- GRB 240930B: Fermi GBM Observation